A method in which a non-contact IC card is introduced into, for example, a railroad ticket gate system and is used when passing through the ticket gate has begun to be put into practical use. FIG. 10 shows an overall configuration of a non-contact IC and a reader/writer device for reading/writing this non-contact IC card. In FIG. 10, reference numeral 200 denotes a reader/writer (R/W) device, and reference numeral 300 denotes a non-contact IC card. Reference numeral 201 denotes a modem, reference numeral 202 denotes a CPU, reference numeral 203 denotes an oscillator, and reference numeral 204 denotes an antenna. Reference numeral 301 denotes an antenna, reference numeral 310 denotes a rectifier, reference numeral 312 denotes a diode, reference numeral 313 denotes a capacitor, reference numeral 320 denotes a modulator, reference numeral 322 denotes an impedance device, reference numeral 323 denotes an FET diode, reference numeral 330 denotes a high-pass filter (HPF), reference numeral 331 denotes a capacitor, reference numeral 332 denotes a resistor, reference numeral 340 denotes a regulator, reference numeral 350 denotes a demodulator, reference numeral 360 denotes a sequencer, and reference numeral 370 denotes a memory.
The R/W device 200 and the IC card 300 of FIG. 10 form a non-contact IC card system in which data is transmitted and received to and from each other via each antenna. In such a non-contact IC card system, the non-contact IC card 300 rectifies a carrier wave modulated in accordance with transmission data from the R/W device 200 in order to generate a DC voltage, and supplies the voltage as power for the internal CPU and circuits such as the memory. Specifically, the voltage rectified by the rectifier 310 is regulated to a predetermined voltage by the regulator 340, and is supplied to the sequencer 360. On the other hand, a signal received by the antenna 301 is demodulated by the demodulator 350 and is supplied to the sequencer 360, where a predetermined process is performed thereon. The processed data is recorded in the memory 370.
Furthermore, when responding to the R/W device 200, in the non-contact IC card 300, the data processed by the sequencer 360 is modulated by the modulator 320, and the data is transmitted from the antenna 301. The signal received by the antenna 204 of the R/W device 200 is demodulated by the modem 201, and the signal is processed by the CPU 202.
In such a non-contact IC card system, IC chips used in a non-contact IC card are formed into one chip by MOS processing, a carrier wave from an external reader/writer is rectified to generate a DC voltage, and the voltage is used as power for the internal CPU and circuits such as the memory.
On the other hand, a mobile communication device having a so-called IC card function, such as a data carrying and processing function, by incorporating an integrated circuit in a mobile communication device has been proposed. However, specific realizing means have not been made clear.